package com.adee.nowcoder.huawei;

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class T009_HJ9 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) { // 注意 while 处理多个 case
            String str = in.nextLine();
            char[] arr = str.toCharArray();
            StringBuilder sb = new StringBuilder();
            Set<Character> set = new HashSet<>();
            for (int i = arr.length-1; i >= 0; i--) {
                if(set.add(arr[i])) {
                    sb.append(arr[i]);
                }
            }
            System.out.println(sb.toString());
        }
    }
}
